Process of making wood pulp



Patented Nov. 26,1929

UNITED "STATES PATENT OFFICE WILLIAM BRYDGES AND SPOTTSWOOD C. FOSTER-I015 I B IG ISLAND, VIRGINIA, ASSIGNORS T BEDFORD PULP 8a PAPER COMPANY, 1110., OF IB'JIGr ISLAND, VIRGINIA PROCESS or MAKING wool) PULP No Drawing.

Our invention. relates to new and useful improvements in the process of making wood pulp for paper making and kindred purposes and more particularly to the treatment of pulp wood in the manufacture of what is generally known in this art as mechanical pulp.

The primary object of the invention resides in the provision of an improved method 10 for the treatment of pine and other coniferous Woods before it is reduced to a pulp by the usual mechanical methods. .7

. A further object of the invention resides in the provision of a process which will eliminate from the wood resin, pitch, turpentine or any other natural or foreign substances therein, and which is designed to neutralize and control acetic or other acids in the wood.

Another object of the invention is to produce means to facilitate the mechanical separation of the wood fibers and to generally improve the properties of the wood pulp from which the paper is .made, so that a stronger sheet of paper may be produced than would be possible fromground wood pulp .or from steamed ground wood pulp.

Still another object is to provide a method which through its treatment of the wood will facilitate the control of the penetration'of so that the paper produced from said pulp will take up more readily the moisture of I steam which is' impinged upon the surface thereof While said paper is beingrun through a machine for crimping, corrugating, folding or is being otherwise deformed, without rupturing, tearing, crushing, or otherwise injuring the paper sheet. v

Another object is to provide a method of treatment of the wood, so that the quantity of pure chemical pulp required for admix ture in the making of the paper may be nmterially reduced over that required for ordinary ground wood pulp, or steamed ground wood pulp, and further, to treatthe Wood in such a manner that less power is required to produce the pulp than is now required with the ground wood process, which is so generally used. I Another object resides in the production moisture of the paper made'from the-pulp,

' Application filed January 18,1929. Serial Ila-333,516.

of a method which will'more readily separate thewood fibers and softenthefwood so that the performance of the grindjstone or other disintegrating devices and'th ke thereof will be greatly enhanced.

With these and numerous otherfobjects in view, our invention consists in the steps in' the process hereinafter and more particularly set forth.

In carrying out our improved method, a closed tank of any desired shape, form or .size is provided, the same being of certain construction as will withstand considerable steam pressure and within this tank there are placed to the capacity of said tankfbolts or blocks of wood which are to be used for the making of the pulp. The tank is also filled with a quantity of alkaline solution, as for instance, soda ash, lime or the like, whereupon steam pressure is admitted to said tank. The pressure of this steam is raised according to the size and condition of the Wood and the length of time the steam pressure is maintained therein also depends upon the size and condition of the wood. The wood in this alkaline solution is thus cooked under the steam pressure and while being so cooked, the gases are vented off and some of the crude oils from the wood may be recovered for com- .mercial use, in the usual or any preferred manner.

This cooking treatment continues for the desired length of time, according to the size and condition of the wood, as stated, and when completed, the remaining liquors from the wood are drawn off from the tank and the steam blown off. The tank is then filled with warm water, generally at about 110 F., and-the wood is retained in this warm water from ten to fifteen hours according to the condition and size of the wood being treated. This warm water treatment over the period of time mentioned may require fresh supplies of water from time to time in order that the treatment may be with Warm water at all times.

This treatment of the wood with warm wa ter is known as an immersion treatment and is for the purpose of washing the wood of alkali, resinous matters and othersubstances.

and also to enable the wood to be fully penetrated, whereby it is softened which facilitates the mechanical separation of the fibers, greatly improves the quality of the pulp, decreases-the amount of power required to produce the pulp, and also increases the amount of pulp which may be produced.

After the immersion process, the wood is removed from the tank and is run through the usual or any form of pulp grinders, such as are now in use, or any other form of disintegrating device, after which the pulp is screened and refined in the usual manner for the purpose of'making paper or other articles of commerce.

As appears from the above method, the wood fibers are readily separated and by the elimination of the resin, pitch and so forth, and the softened condition of the wood, the grinding surfaces of the grind-stones or other disintegrating devices which may be used for carrying out this process, do not require as frequent dressing or attention as usual. Frequent dressing or sharpening causes the wearing away of the grinding or disintegrating device and this wear also causes wear upon the piping, pumps, valves and so forth of the system by abrasion, so that this is eliminated through our improved method. By reducing the acid in the wood through our process, less corrosion of the parts of the system will occur and the pulp and paper making felts and wires will remain cleaner than is ordinarily true, since the impurities and extraneous matters are removed from the wood through our improved .process.

From the foregoing description of the steps of our improved process, the practicing thereof will be readily understood and it will be seen that we have provided a simple, inexpensive and thoroughly efficient means for carrying out the objects of theinvention.

Having thus described our invention, what we claim is:

1. The treatment of wood for making pulp consisting in subjecting blocks or. bolts of wood to an alkaline solution, cooking the wood to remove oils and acids therefrom and washing the wood with warm water to remove extraneous matters and facilitate mechanical separation of the fibers, preparatory to grinding.

2. The treatment of wood for making pulp consisting in subjecting blocks or bolts of wood to an alkaline solution, applying steam pressure to the wood for removal ofoils and acids therefrom and washing the wood with warm water to remove extraneous matters and facilitate mechanical separation of the fibers, preparatory to grinding.

3. The treatment of wood for making pulp consisting in subjecting blocks or bolts of wood toan alkaline solution, applying steam pressure to the wood to cook the same and remove oils and acids therefrom and immersaver/sea ing the wood in warm water for a considerable period of time to remove extraneous matters and facilitate mechanical separation of the fibers of said wood, preparatory to grinding.

4. The treatment of wood for making pulp consisting in introducing blocks or bolts of wood to a closed tank, filling the tank with analkaline solution, applying steam pressure within said tank and maintaining same therein according to the size and condition of the wood, removing gases and liquors from the tank and filling the tank with warm water to completely immerse the wood therein preparatory to grinding, as and for the purposes described.

5. The treatment of wood for making pulp for corrugated boards consisting in first introducing blocks of wood to a closed tank, filling the tank with an alkaline solution, applying steam within said tank and maintaining the same therein for a predetermined length of-time to cook, the wood, exhausting gases and recovering crude oils from said tank at predetermined intervals, draining all liquors from said tank, refilling said tank with warm water to immerse the blocks, substituting heated water for-the water in said tank as the latter cools from time to time to keep the blocks in the immersion treatment under a predetermined temperature and removing the blocks from said tank preparatory to grinding.

In testimony whereof we ai'fix our sig- WILLIAM BRYDGES. SPOTTSlVOOD C. FOSTER.

' natures. 

